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Capsella bursa-pastoris (L.) Medik, shepherd’s purse, is a cosmopolitan summer or winter annual weed species distributed throughout temperate and subtropical regions of the world and is considered one of the most common plants on earth. It is an opportunistic annual that colonizes newly disturbed, open or dry environments and is ubiquitous in cultivated lands in Canada. In annual crops in western Canada, C. bursa-pastoris has been among the 20 most abundant weeds since the first weed surveys in 1970. It is most easily distinguished by its small white four-petalled flowers and its heart-shaped seed-pods, but exhibits considerable variation in leaf shape and flowering time. It has been used for food and medicine by numerous cultures. Its golden-brown seeds are produced in large numbers predominantly through self-pollination and can form a substantial seed bank, with reported values ranging to several hundred thousand seeds m−2. While seeds usually disperse near the mother plant, long-distance dispersal by attaching to vehicles, people and other vectors may be facilitated by its mucilaginous coat. Capsella bursa-pastoris does not produce fertile hybrids with other species of economic or ecological significance. It is generally well controlled by soil-applied and foliar (post-emergence) herbicides although its presence in agricultural fields may result in substantial yield loss, as documented in cole crops in North America and grain crops in Europe. The species can host a wide range of insect, nematode, fungal, viral, and bacterial pests that may damage crop species.

Glyphosate’s efficacy is influenced by the amount absorbed and translocated throughout the plant to inhibit 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS). Glyphosate resistance can be due to target-site (TS) or non–target site (NTS) resistance mechanisms. TS resistance includes an altered target site and gene overexpression, while NTS resistance includes reduced absorption, reduced translocation, enhanced metabolism, and exclusion/sequestration. The goal of this research was to elucidate the mechanism(s) of glyphosate resistance in common ragweed (Ambrosia artemisiifolia L.) from Ontario, Canada. The resistance factor for this glyphosate-resistant (GR) A. artemisiifolia biotype is 5.1. No amino acid substitutions were found at positions 102 or 106 of the EPSPS enzyme in this A. artemisiifolia biotype. Based on [14C]glyphosate studies, there was no difference in glyphosate absorption or translocation between glyphosate-susceptible (GS) and GR A. artemisiifolia biotypes. Radio-labeled glyphosate metabolites were similar for GS and GR A. artemisiifolia 96 h after application. Glyphosate resistance in this A. artemisiifolia biotype is not due to an altered target site due to amino acid substitutions at positions 102 and 106 in the EPSPS and is not due to the NTS mechanisms of reduced absorption, reduced translocation, or enhanced metabolism.

Plant evolution has been a complex process involving hybridization and polyploidization making understanding the origin and evolution of a plant’s genome challenging even once a published genome is available. The oilseed crop, Camelina sativa (Brassicaceae), has a fully sequenced allohexaploid genome with 3 unknown ancestors. To better understand which extant species best represent the ancestral genomes that contributed to C. sativa’s formation, we sequenced and assembled chromosome level draft genomes for 4 diploid members of Camelina: C. neglecta C. hispida var. hispida, C. hispida var. grandiflora, and C. laxa using long and short read data scaffolded with proximity data. We then conducted phylogenetic analyses on regions of synteny and on genes described for Arabidopsis thaliana, from across each nuclear genome and the chloroplasts to examine evolutionary relationships within Camelina and Camelineae. We conclude that C. neglecta is closely related to C. sativa’s sub-genome 1 and that C. hispida var. hispida and C. hispida var. grandiflora are most closely related to C. sativa’s sub-genome 3. Further, the abundance and density of transposable elements, specifically Helitrons, suggest that the progenitor genome that contributed C. sativa’s sub-genome 3 maybe more similar to the genome of C. hispida var. hispida than that of C. hispida var. grandiflora. These diploid genomes show few structural differences when compared to C. sativa’s genome indicating little change to chromosome structure following allopolyploidization. This work also indicates that C. neglecta and C. hispida are important resources for understanding the genetics of C. sativa and potential resources for crop improvement.

Kochia, a major weed species, has evolved resistance to four herbicide modes of action. Herbicide resistance appears to spread quickly, which could result in diminished standing genetic variation, reducing the ability of populations to adapt further. Here we used double digest restriction enzyme associated sequencing to determine the level of gene flow among kochia populations and whether selection for glyphosate resistance reduces genetic variation. Canadian Prairie populations show little to no genetic differentiation (FST = 0.01) and no correlation between genetic and geographic distance (r2 = − 0.02 p = 0.56), indicating high gene flow and no population structure. There is some evidence that kochia populations are genetically depauperate compared to other weed species, but genetic diversity did not differ between glyphosate susceptible and resistant populations or individuals. The inbreeding coefficients suggest there are 23% fewer heterozygotes in these populations than expected with random mating, and no variation was found within the chloroplast. These results indicate that any alleles for herbicide resistance can be expected to spread quickly through kochia populations, but there is little evidence this spread will reduce the species’ genetic variation or limit the species’ ability to respond to further selection pressure.

It is important to understand the probability of hybridization and potential for introgression of transgenic crop alleles into wild populations as part of pre-release risk assessment. Here we completed bidirectional crosses between the emerging crop, camelina [Camelina sativa (L.) Crantz] and its weedy relative, ball mustard [Neslia paniculata (L.) Desv.]. Ball mustard is a self-compatible annual that produces hard ball-like seeds similar to canola or mustard seed in size and shape. A total of 1593 crosses were completed and collected with camelina as the maternal parent, while 3253 crosses were successfully collected in the reverse direction. Putatively hybrid seedlings were screened with flow cytometry and species-specific nuclear ribosomal internal transcribed spacer (ITS) markers. Three plants had DNA contents close to expectations for hybrids, but only one of these, formed on camelina, had the expected ITS markers. This hybrid exhibited low fertility, and neither self-pollination nor backcrossing produced viable progeny. The other two plants, formed on ball mustard, had high pollen and seed fertility and were identified as ball mustard neoautotetraploids. Therefore, the hybridization rate between camelina and ball mustard is relatively low at one in 20 000 ovules pollinated when camelina is the maternal parent. However, autotetraploids may form frequently in ball mustard, and tetraploid populations may exist in nature.

Here we present a revised species checklist for the Brassicaceae, updated from Warwick SI, Francis, A, Al-Shehbaz IA (2006), Brassicaceae: Species checklist and database on CD-ROM, Plant Systematics and Evolution 259: 249─25. This update of the checklist was initiated, based on recent taxonomic and molecular studies on the Brassicaceae that have resulted in new species names, combinations and associated synonyms. New data have been added indicating tribal affiliations within the family and where type specimens have been designated. In addition, information from many early publications has been checked and added to the database. The database now includes information on 14983 taxa, 4636 of which are currently accepted and divided into 340 genera and 52 tribes. A selected bibliography of recent publications on the Brassicaceae is included.

Atriplex hortensis (2n = 2x = 18, 1C genome size 1.1 gigabases), also known as garden orach and mountain-spinach, is a highly nutritious, broadleaf annual of the Amaranthaceae-Chenopodiaceae alliance (Chenopodiaceae sensu stricto, subfam. Chenopodioideae) that has spread in cultivation from its native primary domestication area in Eurasia to other temperate and subtropical regions worldwide. Atriplex L. is a highly complex but, as understood now, a monophyletic group of mainly halophytic and/or xerophytic plants, of which A. hortensis has been a vegetable of minor importance in some areas of Eurasia (from Central Asia to the Mediterranean) at least since antiquity. Nonetheless, it is a crop with tremendous nutritional potential due primarily to its exceptional leaf and seed protein quantities (approaching 30%) and quality (high levels of lysine). Although there is some literature describing the taxonomy and production of A. hortensis, there is a general lack of genetic and genomic data that would otherwise help elucidate the genetic variation, phylogenetic positioning, and future potential of the species. Here, we report the assembly of the first high-quality, chromosome-scale reference genome for A. hortensis cv. “Golden.” Long-read data from Oxford Nanopore’s MinION DNA sequencer was assembled with the program Canu and polished with Illumina short reads. Contigs were scaffolded to chromosome scale using chromatin-proximity maps (Hi-C) yielding a final assembly containing 1,325 scaffolds with a N50 of 98.9 Mb – with 94.7% of the assembly represented in the nine largest, chromosome-scale scaffolds. Sixty-six percent of the genome was classified as highly repetitive DNA, with the most common repetitive elements being Gypsy- (32%) and Copia-like (11%) long-terminal repeats. The annotation was completed using MAKER which identified 37,083 gene models and 2,555 tRNA genes. Completeness of the genome, assessed using the Benchmarking Universal Single Copy Orthologs (BUSCO) metric, identified 97.5% of the conserved orthologs as complete, with only 2.2% being duplicated, reflecting the diploid nature of A. hortensis. A resequencing panel of 21 wild, unimproved and cultivated A. hortensis accessions revealed three distinct populations with little variation within subpopulations. These resources provide vital information to better understand A. hortensis and facilitate future study.

Hybridization between crops and their wild relatives has the potential to introduce novel variation into wild populations. Camelina (Camelina sativa) is a promising oilseed and cultivars with modified seed characteristics and herbicide resistance are in development, prompting a need to evaluate the potential for novel trait introgression into weedy relatives. Little‐podded false flax (littlepod; Camelina microcarpa) is a naturalized weed in Canada and the USA. Here we evaluated the hybridization rate between the three cytotypes of littlepod (♀) and camelina (♂), assessed characteristics of hybrids, and evaluated the fitness of hexaploid littlepod and camelina hybrids in the glasshouse and field. In total we conducted, 1,005 manual crosses with diploid littlepod, 1, 172 crosses with tetraploid littlepod, and 896 crosses with hexaploid littlepod. Hybrids were not produced by the diploids, but were produced by the tetraploids and hexaploids at rates of one hybrid for 2,000 ovules pollinated and 24 hybrids for 25 ovules pollinated, respectively. Hybrids between tetraploid littlepod and camelina showed low pollen fertility and produced a small number of seeds. In the glasshouse, hybrids between hexaploid littlepod and camelina also showed significantly lower pollen fertility and seed production than parental lines, but their seeds showed high viability. A similar pattern was observed in field trials, with hybrids showing earlier flowering, reduced biomass, seed production and seed weight. However, seed produced by the hybrids showed greater viability than that produced by hexaploid littlepod and is potentially the result of a shortened lifecycle. The introgression of lifecycle traits into littlepod populations may facilitate range expansion and contribute to crop gene persistence. Consequently, future work should evaluate the hybridization rate in the field, the fitness of advanced generation backcrosses, and the role of time to maturity in limiting hexaploid littlepod's distribution.

Two bioactive omega-3, long-chain, fatty acids (EPA and DHA), found in algal and fish oils, can now be produced in genetically engineered (GE) terrestrial oilseed crops. These fatty acids are involved in key physiological functions in invertebrates and vertebrates. They are known to be synthesized by primary producers in aquatic ecosystems, but not by terrestrial crop plants. Thus, the production of EPA and DHA by GE seed oil crops represents a fundamental shift in the accessibility of bioactive fatty acids to terrestrial consumers; one that may change their physiology and survival thereby altering ecological interactions among terrestrial organisms. Here we discuss the potential ecological and evolutionary consequences of the novel production of EPA and DHA by GE oilseed crops.

The distribution and abundance of three Camelina species introduced to Canada is unknown, but critical for evaluating the risks associated with unconfined release of transgenic Camelina sativa (L.) Crantz (2n = 40). Furthermore, previous reports suggest Canadian populations of Camelina microcarpa Andrz. ex DC. vary for ploidy and ability to hybridize with C. sativa. We completed 8 weeks of field work in Alberta, Saskatchewan, Manitoba, southern Ontario, Quebec, and the Maritimes. We determined the ploidy composition of the populations found. We did not locate Camelina alyssum (Mill.) Thell., but located four sites with C. sativa and 34 with C. microcarpa. Eleven C. microcarpa populations were tetraploid (2n = 26, 1.00pg/2C) and 22 were hexaploid (2n = 40, 1.50pg/2C), while two populations were mixed. We examined material from botanical gardens and plant gene resource centres assessing total nuclear DNA content and completing chromosome counts for each species and cytotype identified, to determine whether tetraploid and hexaploid C. microcarpa were included in these collections. No tetraploid material was included in the C. microcarpa accessions received; however, a diploid (2n = 12, 0.54pg/2C) was found. Given the current geographic ranges, abundance, and chromosome counts of these species, the greatest risk of hybridization with transgenic C. sativa is from hexaploid C. microcarpa.

Background Due to the accessibility of underlying technologies the 'Omics', in particular genomics, are becoming commonplace in several fields of research, including the study of agricultural pests. The weed community is starting to embrace these approaches; genome sequences have been made available in the past years, with several other sequencing projects underway, as promoted by the International Weed Genome Consortium. Chromosome-scale sequences are essential to fully exploit the power of genetics and genomics. Results We report such an assembly for Conyza canadensis, an important agricultural weed. Third-generation sequencing technology was used to create a genome assembly of 426 megabases, of which nine chromosome-scale scaffolds cover more than 98% of the entire assembled sequence. As this weed was the first to be identified with glyphosate resistance, and since we do not have a firm handle on the genetic mechanisms responsible for several herbicide resistances in the species, the genome sequence was annotated with genes known to be associated with herbicide resistance. A high number of ABC-type transporters, cytochrome P450 and glycosyltransferases (159, 352 and 181, respectively) were identified among the list of ab initio predicted genes. Conclusion As C. canadensis has a small genome that is syntenic with other Asteraceaes, has a short life cycle and is relatively easy to cross, it has the potential to become a model weed species and, with the chromosome-scale genome sequence, contribute to a paradigm shift in the way non-target site resistance is studied. © 2020 Her Majesty the Queen in Right of CanadaPest Management Science © 2020 Society of Chemical Industry.

We compared the secondary metabolite composition in seeds of Camelina sativa and its wild relatives to identify potential germplasm with reduced levels of antinutritional compounds. Twenty Camelina accessions, from five different species, were analyzed by liquid chromatography mass spectrometry and subjected to principal component analysis, which revealed that Camelina spp. separated into distinct chemotaxonomic groups. Three major glucosinolates (GSs) were identified in our study, namely, 9-methylsulfinylnonyl GS (GS9), 10-methylsulfinyldecyl GS (GS10), and 11-methylsulfinylundecyl GS (GS11). While there were differences in total GS levels, species-specific patterns for GS9 and GS11 were noted. Sinapine content ranged between 1.4 and 5.6 mg/g FW, with the lowest levels observed in C. laxa and C. sativa. Lignin levels were also lowest in C. sativa, with most accessions containing less than 6 mg/g FW. Our results show that wild Camelina spp. have distinct metabolomes, and based on their levels of major antinutritionals, some could be incorporated into breeding programs with C. sativa.

Hybridization between crops and their wild relatives has the potential to introduce novel variation into wild populations. Camelina (Camelina sativa) is a promising oilseed and cultivars with modified seed characteristics and herbicide resistance are in development, prompting a need to evaluate the potential for novel trait introgression into weedy relatives. Little‐podded false flax (littlepod; Camelina microcarpa) is a naturalized weed in Canada and the USA. Here we evaluated the hybridization rate between the three cytotypes of littlepod (♀) and camelina (♂), assessed characteristics of hybrids, and evaluated the fitness of hexaploid littlepod and camelina hybrids in the glasshouse and field. In total we conducted, 1,005 manual crosses with diploid littlepod, 1, 172 crosses with tetraploid littlepod, and 896 crosses with hexaploid littlepod. Hybrids were not produced by the diploids, but were produced by the tetraploids and hexaploids at rates of one hybrid for 2,000 ovules pollinated and 24 hybrids for 25 ovules pollinated, respectively. Hybrids between tetraploid littlepod and camelina showed low pollen fertility and produced a small number of seeds. In the glasshouse, hybrids between hexaploid littlepod and camelina also showed significantly lower pollen fertility and seed production than parental lines, but their seeds showed high viability. A similar pattern was observed in field trials, with hybrids showing earlier flowering, reduced biomass, seed production and seed weight. However, seed produced by the hybrids showed greater viability than that produced by hexaploid littlepod and is potentially the result of a shortened lifecycle. The introgression of lifecycle traits into littlepod populations may facilitate range expansion and contribute to crop gene persistence. Consequently, future work should evaluate the hybridization rate in the field, the fitness of advanced generation backcrosses, and the role of time to maturity in limiting hexaploid littlepod's distribution.

The development of transgenic oilseed Camelina sativa (2n = 40) and the potential for hybridization with its weedy relative Capsella bursa-pastoris (2n = 36) necessitates a careful evaluation of the reproductive compatibility between the species. Here, we conducted over 1800 crosses (emasculation and manual pollination) to examine the ability of 10 Canadian C. bursa-pastoris (♀) accessions to hybridize with five accessions of C. sativa (♂). Seven hybrids were confirmed among 586 putative hybrids screened with species-specific markers, indicating a hybridization rate of 1.5 hybrids per 10 000 ovules pollinated. All seven hybrids had intermediate DNA content compared to their parents, were morphologically distinct, had low (1.9%) pollen fertility and failed to produce selfed or backcrossed seed. Given the abundance of C. bursa-pastoris along field margins, hybrids will likely be generated in the wild, but they will be unable to establish lineages unless fertility is restored. The large number of crosses and the diversity captured by the use of multiple accessions resulted in strong statistical power and a high degree of confidence in the estimated hybridization rate.

With transgenic crop development it is important to evaluate the potential for transgenes to escape into populations of wild, weedy relatives. Ethiopian mustard (Brassica carinata, BBCC) is easily transformed and is being investigated for uses from biodiesel fuels to biopharmaceuticals. However, little work has been done evaluating its ability to cross with relatives such as wild mustard (Sinapsis arvensis, SrSr), an abundant, cosmopolitan weedy relative. Here we conducted bidirectional crosses with Ethiopian mustard as a maternal parent in 997 crosses and paternal parent in 1,109 crosses. Hybrids were confirmed using flow cytometry and species-specific ITS molecular markers and indicate a high hybridization rate of 6.43 % between Ethiopian mustard (♀) and wild mustard (♂) and a lower, but not insignificant, hybridization rate of 0.01 % in the reverse direction. The majority of the hybrids were homoploid (BCSr) with less than 1 % of pollen production of their parents and low seed production (0.26 seeds/pollination) in crosses and backcrosses indicating a potential for advanced generation hybrids. The accession used had a significant effect on hybrid seed production with different accessions of Ethopian mustard varying in their production of hybrid offspring from 2.69 to 16.34 % and one accession of wild mustard siring almost twice as many hybrid offspring per flower as the other. One pentaploid (BBCCSr) and one hexaploid (BBCCSrSr) hybrid were produced and had higher pollen viability, though no and low seed production, respectively. As wild mustard is self-incompatible and the outcrossing rate of Ethiopian mustard has been estimated as 30 % potential for hybrid production in the wild appears to be high, though the hybridization rate found here represents a worst case scenario as it does not incorporate pre-pollination barriers. Hybridization in the wild needs to be directly evaluated as does the propensity of Ethiopian mustard to volunteer.

Glyphosate is considered the world’s most important herbicide, but widespread and continual use has resulted in the evolution of resistance. Kochia scoparia (kochia) has evolved resistance via tandem gene amplification of glyphosate’s target, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) and resistant populations have been reported from the Canadian Prairies and the Northern Great Plains. Here, we evaluated the fitness costs of EPSPS amplification in kochia by comparing susceptible and resistant full siblings from segregating F2 populations generated from within six populations. Kochia was expected to be highly diverse because of strong gene flow; however, six of the seven field-collected parents with higher EPSPS copy number were homozygous. Under competitive greenhouse conditions, the EPSPS type of the line’s maternal parent showed persistent effects: delayed emergence, delayed flowering, and reductions in viable seed count and weight overall. High EPSPS copy number individuals had reduced seed count and weight, reduced competitive ability, and reduced final height in mixed stands, but better germination of the F3. However, all characteristics were highly variable and fitness costs were not constant across genetic backgrounds. In the absence of selection from glyphosate, kochia with increased EPSPS copy number will be at a competitive disadvantage in some genetic backgrounds.

Interest in the magnitude and consequences of intra- and inter-specific herbicide resistance gene flow, particularly that mediated by pollen, increased in the mid-1990s with the introduction of herbicide-resistant (HR) transgenic crops. During that time, less attention was paid to the movement of HR alleles via pollen or seed among weed populations. Incidence of HR weeds in a region is often attributed to independent evolution through herbicide selection; the role or contribution of HR allele movement via pollen, seeds and/or vegetative propagules is often under-estimated and under-appreciated. Once a new HR weed biotype has been confirmed in a jurisdiction, how often have we been surprised at its rapid areawide expansion? In genotypic studies of HR weed populations, the contribution of gene flow to incidence of resistance is frequently similar or greater than that of independent evolution. Simulation models have consistently predicted that frequent widespread applications of highly effective herbicides ( e.g., acetolactate synthase inhibitors, glyphosate) provide connective high-fitness habitats across the landscape, which facilitate a rapid increase in the frequency and movement of an HR trait within and among populations. Such habitats, characterized by minimal heterogeneity but high selection intensity due to frequent herbicide ‘on’ vs. ‘off’ exposure periods, strongly favour the fitness of HR propagules at great disadvantage of herbicide-susceptible individuals. The unanticipated speed of areawide expansion of some HR weed biotypes has spurred numerous calls over the past decade for a collective community or regional response to mitigate this unhindered spread of HR alleles. The best mitigation strategy is minimizing weed population abundance and seed bank replenishment in fields and adjacent ruderal areas. This goal is difficult, but necessary for preserving the remaining public good and common pool resource of herbicide susceptibility.

Background Synoptic circulation patterns (large-scale weather systems) affect ambient levels of air pollution, as well as the relationship between air pollution and human health. Objective To investigate the air pollution–mortality relationship within weather types and seasons, and to determine which combination of atmospheric conditions may pose increased health threats in the elderly age categories. Methods The relative risk of mortality (RR) due to air pollution was examined using Poisson generalized linear models (GLMs) within specific weather types. Analysis was completed by weather type and age group (all ages, ≤64, 65–74, 75–84, ≥85 years) in ten Canadian cities from 1981 to 1999. Results There was significant modification of RR by weather type and age. When examining the entire population, weather type was shown to have the greatest modifying effect on the risk of dying due to ozone (O3). This effect was highest on average for the dry tropical (DT) weather type, with the all-age RR of mortality at a population weighted mean (PWM) found to be 1.055 (95% CI 1.026–1.085). All-weather type risk estimates increased with age due to exposure to carbon monoxide (CO), nitrogen dioxide (NO2), and sulphur dioxide (SO2). On average, RR increased by 2.6, 3.8 and 1.5% for the respective pollutants between the ≤64 and ≥85 age categories. Conversely, mean ozone estimates remained relatively consistent with age. Elevated levels of air pollution were found to be detrimental to the health of elderly individuals for all weather types. However, the entire population was negatively effected by air pollution on the hot dry (DT) and hot humid (MT) days. Conclusions We identified a significant modification of RR for mortality due to air pollution by age, which is enhanced under specific weather types. Efforts should be targeted at minimizing pollutant exposure to the elderly and/or all age groups with respect to weather type in question.

Gene flow from acetolactate synthase-resistant (HR) Brassica juncea oilseed canola to related weed, Sinapis arvensis (density 1 plant/m2) was assessed in a 100 m2 field plot of HR B. juncea. Two HR F1 hybrids (H1 and H2) were detected among 109 951 seedlings screened with imazethapyr (hybridization frequency – 1.8 × 10−5). Hybridity was confirmed using flow cytometry, B. juncea-specific amplified fragment length polymorphisms (AFLPs) markers, genomic in situ hybridization (GISH) and PCR-based detection of B. juncea's HR gene. H1 and H2 had 2n = 27 and 2n = 45 chromosomes, corresponding 3x (SrAB) and 5x (SrAABB) genomic structures and reduced male fertility, 3.2 and 16.6% pollen viability, respectively. H1 was self-incompatible, whereas H2 set seed when selfed (B. juncea trait). Selfed F2, F3 and F4 plants showed HR trait persistence and vigorous growth and high (80–100%) pollen fertility in 22% and 39% of the F2 and F3 plants, respectively. No progeny were obtained from F1, F2 or F3 hybrids × S. arvensis backcrosses, suggesting the likelihood of introgression of traits is low to negligible.

Polyploid organisms often have different geographic ranges than their diploid relatives. However, it is unclear whether this divergence is maintained by adaptation or results from historical differences in colonization. Here, we conducted a reciprocal transplant experiment with diploid and autotetraploid Chamerion angustifolium to test for adaptation at the ploidy and population level. In the Rocky Mountains, pure diploid populations occur at high elevations and pure autotetraploid populations occur at low elevations with mixed ploidy populations between. We planted 3134 seedlings in 2004 and 3890 juveniles (bolting) in 2005 among nine plots, three in each of the diploid, mixed ploidy, and tetraploid zones, and monitored survival until 2008. For both seedlings and juvenile plants, elevation significantly influenced survival. The juvenile plants also showed a significant ploidy by elevation interaction, indicating that diploids and tetraploids survived best at their native elevations. In contrast, we found no evidence of local adaptation to plot within elevation. This suggests that the current distribution of diploids and tetraploids across elevations is the result of adaptation and that genome duplication may have facilitated the invasion of lower elevation habitats by limiting the movement of maladapted alleles from diploid populations at higher elevations.

Genome size is an indicator of evolutionary distance and a metric for genome characterization. Here, we report accurate estimates of genome size in 99 accessions from 26 species of Avena. We demonstrate that the average genome size of C genome diploid species (2C = 10.26 pg) is 15% larger than that of A genome species (2C = 8.95 pg), and that this difference likely accounts for a progression of size among tetraploid species, where AB < AC < CC (average 2C = 16.76, 18.60, and 21.78 pg, respectively). All accessions from three hexaploid species with the ACD genome configuration had similar genome sizes (average 2C = 25.74 pg). Genome size was mostly consistent within species and in general agreement with current information about evolutionary distance among species. Results also suggest that most of the polyploid species in Avena have experienced genome downsizing in relation to their diploid progenitors. Genome size measurements could provide additional quality control for species identification in germplasm collections, especially in cases where diploid and polyploid species have similar morphology.

Premise of the study Despite advantages in terms of reproducibility, histogram analysis based on nonlinear regression is rarely used in genome size assessments in plant biology. This is due in part to the lack of a freely available program to implement the procedure. We have developed such a program, the R package flowPloidy. Methods and results flowPloidy builds on the existing statistical tools provided with the R environment. This base provides tools for importing flow cytometry data, fitting nonlinear regressions, and interactively visualizing data. flowPloidy adds tools for building flow cytometry models, fitting the models to histogram data, and producing visual and tabular summaries of the results. Conclusions flowPloidy fills an important gap in the study of plant genome size. This package will enable plant scientists to apply a more powerful statistical technique for assessing genome size. flowPloidy improves on existing software options by providing a no-cost workflow streamlined for genome size and ploidy determination.

Our goal is to develop an instrument for parallel and multiplexed bioassay using magnetic labels. Toward this end we are developing a multi-outlet magnetophoresis instrument incorporating a fluidic flow chamber placed inside a magnetic field gradient. Magnetic microparticles are sorted by their magnetic moment for eventual use as biological labels based on magnetic signature. In this paper, we concentrate on developments in our flow chamber fabrication methods that have allowed us to scale the number of sorting channels from 8 to 25. We present data for instrument performance and reproducibility of sorting.

The evolutionary transition from diploidy to polyploidy is prevalent in flowering plants and may result in correlated changes in mating system (outcrossing rate). Most theory predicts a shift toward self‐fertilization (decrease in outcrossing) in polyploids, but empirical evidence for this pattern and its underlying mechanisms is inconclusive or restricted to a few cases. In an analysis of variation in outcrossing rates among diploid‐polyploid species pairs from the literature, polyploids had lower outcrossing rates (higher selfing; \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \Declar...

Whole genome duplications have occurred recurrently throughout the evolutionary history of eukaryotes. The resulting genetic and phenotypic changes can influence physiological and ecological responses to the environment; however, the impact of genome copy number on evolvability has rarely been examined experimentally. Here, we evaluate the effect of genome duplication on the ability to respond to selection for early flowering time in lines drawn from naturally occurring diploid and autotetraploid populations of the plant Chamerion angustifolium (fireweed). We contrast this with the result of four generations of selection on synthesized neoautotetraploids, whose genic variability is similar to diploids but genome copy number is similar to autotetraploids. In addition, we examine correlated responses to selection in all three groups. Diploid and both extant tetraploid and neoautotetraploid lines responded to selection with significant reductions in time to flowering. Evolvability, measured as realized heritability, was significantly lower in extant tetraploids (^b(T) = 0.31) than diploids (^b(T) = 0.40). Neotetraploids exhibited the highest evolutionary response (^b(T) = 0.55). The rapid shift in flowering time in neotetraploids was associated with an increase in phenotypic variability across generations, but not with change in genome size or phenotypic correlations among traits. Our results suggest that whole genome duplications, without hybridization, may initially alter evolutionary rate, and that the dynamic nature of neoautopolyploids may contribute to the prevalence of polyploidy throughout eukaryotes.

Polyploid organisms often have different geographic ranges than their diploid relatives. However, it is unclear whether this divergence is maintained by adaptation or results from historical differences in colonization. Here, we conducted a reciprocal transplant experiment with diploid and autotetraploid Chamerion angustifolium to test for adaptation at the ploidy and population level. In the Rocky Mountains, pure diploid populations occur at high elevations and pure autotetraploid populations occur at low elevations with mixed ploidy populations between. We planted 3134 seedlings in 2004 and 3890 juveniles (bolting) in 2005 among nine plots, three in each of the diploid, mixed ploidy, and tetraploid zones, and monitored survival until 2008. For both seedlings and juvenile plants, elevation significantly influenced survival. The juvenile plants also showed a significant ploidy by elevation interaction, indicating that diploids and tetraploids survived best at their native elevations. In contrast, we found no evidence of local adaptation to plot within elevation. This suggests that the current distribution of diploids and tetraploids across elevations is the result of adaptation and that genome duplication may have facilitated the invasion of lower elevation habitats by limiting the movement of maladapted alleles from diploid populations at higher elevations.

Sabit Cakmak1, Sara L. Martin4, Claudia Blanco Vidal2, Timur Gultekin3, Vladislav Brion4 and Maria Angelica Rubio5 1Health Canada, Ottawa, Department of Statistics, 2Area Descontaminacion Atmosferica, Comision Nacional del Medio Ambiente (CONAMA), 3Department of Anthropology, Ankara University, 4Health Canada, Ottawa, Department of Statistics 5Departamento de Ciencias del Ambiente, Facultad de Quimica y Biologia, Universidad de Santiago de Chile Centro de Desarrollo para la Nanociencia y Nanotecnologia (CEDENNA), 1,4Canada 2,5Chile 3Turkey

The environmental changes caused by climate change represent a significant challenge to human societies. One part of this challenge will be greater heat-related mortality. Populations in the northern hemisphere will experience temperature increases exceeding the global average, but whether this will increase or decrease total temperature-related mortality burdens is debated. Here, we use distributed lag modeling to characterize temperature-mortality relationships in 15 Canadian cities. Further, we examine historical trends in temperature variation across Canada. We then develop city-specific general linear models to estimate change in high- and low-temperature-related mortality using dynamically downscaled climate projections for four future periods centred on 2040, 2060 and 2080. We find that the minimum mortality temperature is frequently located at approximately the 75th percentile of the city’s temperature distribution, and that Canadians currently experience greater and longer lasting risk from cold-related than heat-related mortality. Additionally, we find no evidence that temperature variation is increasing in Canada. However, the projected increased temperatures are sufficient to change the relative levels of heat- and cold-related mortality in some cities. While most temperature-related mortality will continue to be cold-related, our models predict that higher temperatures will increase the burden of annual temperature-related mortality in Hamilton, London, Montreal and Regina, but result in slight to moderate decreases in the burden of mortality in the other 11 cities investigated.